platform/x86/intel/pmt: Add PMT Discovery driver

This patch introduces a new driver to enumerate and expose Intel Platform
Monitoring Technology (PMT) capabilities via a simple discovery mechanism.
The PMT Discovery driver parses hardware-provided discovery tables from
Intel Out of Band Management Services Modules (OOBMSM) and extracts feature
information for various providers (such as TPMI, Telemetry, Crash Log,
etc). This unified interface simplifies the process of determining which
manageability and telemetry features are supported by a given platform.

This new feature is described in the Intel Platform Monitoring Technology
3.0 specification, section 6.6 Capability.

Key changes and additions:

New file drivers/platform/x86/intel/pmt/discovery.c:
  – Implements the discovery logic to map the discovery resource, read
    the feature discovery table, and validate feature parameters.
New file drivers/platform/x86/intel/pmt/features.c:
  – Defines feature names, layouts, and associated capability masks.
  – Provides a mapping between raw hardware attributes and sysfs
    representations for easier integration with user-space tools.
New header include/linux/intel_pmt_features.h:
  – Declares constants, masks, and feature identifiers used across the
    PMT framework.
Sysfs integration:
  – Feature attributes are exposed under /sys/class/intel_pmt.
  – Each device is represented by a subfolder within the intel_pmt class,
    named using its DBDF (Domain:Bus:Device.Function), e.g.:
        features-0000:00:03.1
  – Example directory layout for a device:

    /sys/class/intel_pmt/features-0000:00:03.1/
    ├── accelerator_telemetry
    ├── crash_log
    ├── per_core_environment_telemetry
    ├── per_core_performance_telemetry
    ├── per_rmid_energy_telemetry
    ├── per_rmid_perf_telemetry
    ├── tpmi_control
    ├── tracing
    └── uncore_telemetry

By exposing PMT feature details through sysfs and integrating with the
existing PMT class, this driver paves the way for more streamlined
integration of PMT-based manageability and telemetry tools.

Link: https://www.intel.com/content/www/us/en/content-details/710389/intel-platform-monitoring-technology-intel-pmt-external-specification.html
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: https://lore.kernel.org/r/20250703022832.1302928-9-david.e.box@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

1 files changed, 33 insertions, 2 deletions

diff --git a/drivers/platform/x86/intel/pmt/class.c b/drivers/platform/x86/intel/pmt/class.c
index 7233b654bbad..a806a81ece52 100644
--- a/drivers/platform/x86/intel/pmt/class.c
+++ b/drivers/platform/x86/intel/pmt/class.c
@@ -9,11 +9,13 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/log2.h>
 #include <linux/intel_vsec.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/pci.h>
+#include <linux/sysfs.h>
 
 #include "class.h"
 
@@ -166,12 +168,41 @@ static struct attribute *intel_pmt_attrs[] = {
 	&dev_attr_offset.attr,
 	NULL
 };
-ATTRIBUTE_GROUPS(intel_pmt);
 
-static struct class intel_pmt_class = {
+static umode_t intel_pmt_attr_visible(struct kobject *kobj,
+				      struct attribute *attr, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct auxiliary_device *auxdev = to_auxiliary_dev(dev->parent);
+	struct intel_vsec_device *ivdev = auxdev_to_ivdev(auxdev);
+
+	/*
+	 * Place the discovery features folder in /sys/class/intel_pmt, but
+	 * exclude the common attributes as they are not applicable.
+	 */
+	if (ivdev->cap_id == ilog2(VSEC_CAP_DISCOVERY))
+		return 0;
+
+	return attr->mode;
+}
+
+static bool intel_pmt_group_visible(struct kobject *kobj)
+{
+	return true;
+}
+DEFINE_SYSFS_GROUP_VISIBLE(intel_pmt);
+
+static const struct attribute_group intel_pmt_group = {
+	.attrs = intel_pmt_attrs,
+	.is_visible = SYSFS_GROUP_VISIBLE(intel_pmt),
+};
+__ATTRIBUTE_GROUPS(intel_pmt);
+
+struct class intel_pmt_class = {
 	.name = "intel_pmt",
 	.dev_groups = intel_pmt_groups,
 };
+EXPORT_SYMBOL_GPL(intel_pmt_class);
 
 static int intel_pmt_populate_entry(struct intel_pmt_entry *entry,
 				    struct intel_vsec_device *ivdev,